


be my detonator

by nilchance



Category: Undertale (Video Game)
Genre: Fake Marriage, Idiots in Love, Kedgeup, M/M, Sex Toys Under Clothing, Underfell Papyrus (Undertale), vaguely leverage-esque criminal au
Language: English
Status: Completed
Published: 2019-05-06
Updated: 2019-05-06
Packaged: 2020-02-27 07:59:46
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,808
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18734893
Author URL: https://archiveofourown.org/users/nilchance/pseuds/nilchance
Summary: Edge needs to stop letting Red come up with the cover stories.





	be my detonator

**Author's Note:**

> detailed content warnings in the endnotes, although only one because this story is light and fluffy and uncomplicated, goddamnit.

Edge has little patience for dance clubs to begin with. Flashing lights, obnoxious music, cramped quarters, too many people. None of them are his idea of a good time, particularly not when he’s working. But after three weeks on the same job, putting in appearances at the club almost every night and working to get the attention of small-time mobsters with delusions of grandeur, he’s ready to burn this place to the ground. 

There is the promise of better prey, even if this is mostly mopping up after the last big job. Whether the marks take them for possible allies or possible victims, they’ll be brought to meet with the real targets, the ones who were trafficking monsters before Papyrus and Red shut down their operations with a literal bang, and Edge’ll finally get to do something that isn’t playing nice with idiots. He’s not particularly good at playing nice. That’s what Sans is for.

Speaking of. Edge has had his eyes on him all night, as he usually does, watching him charm and joke and play the fool, as dangerous with a disarming grin on his face as Edge is with a weapon in his hand. He’s pretending to be drunk, stumbling a little on his feet and laughing too loud. Smart, although he probably should’ve made it a point to circle back to check in with Edge more frequently throughout the night. They are newlyweds, after all. How quickly the romance fades.

(He really needs to stop letting Red come up with their cover stories.)

Briefly, Sans meets his eyes through the crowd. Edge smiles and crooks a finger, beckoning him. Sans gives him a sweet, indulgent smile and turns to the person he was chatting up to make his excuses. A moment later, he’s weaving his way across the floor, all indolent slouch and easy grin. It isn't until Edge gets close that he can see the way his eyelights are a little unfocused and the slight strain in his smile. He'd never know about the cunning little vibrator nestled against Sans's clit if Sans hadn’t handed him the remote himself.

Playing along with this game is not Edge’s most well-considered decision, but Sans pointed out that neither of them are at their best when they’re bored, and this certainly keeps things interesting. Edge was not hard to convince. Sans is a terrible influence.

"hi, pumpkin," Sans says, sitting down beside him. His leg presses against Edge's, a very faint tremor in it. "how's tricks?"

"I'm having a lovely evening," Edge says. In the pocket of his jacket, he gently nudges the dial of the remote higher and watches Sans swallow hard and close his eyes. "And you?"

"heh." Sans lays his head back against the wall. His voice is barely audible beneath the monotonous pounding of the music, pitched to carry only to Edge. "well, i'm thinking about killing my husband."

"Are you now?" Edge asks. "That's a shame. I hear the sex is amazing."

"i'm..." Sans falters for a comeback, which tells Edge all he needs to know. Sans is at the end of his rope, and it's time for them to leave. "yeah. it's pretty great, but it turns out the guy is a kinky bastard. some real marquis de sade shit."

"How terrible for you," Edge says. Gently, he turns Sans's face towards him and kisses him. Sans kisses back, desperate and hungry, and Edge smiles against his mouth. "Would you like to come home with me instead?"

"i dunno,” Sans says, yearning towards him. “you might be a serial killer. the sexy ones always are.”

“I assure you that if I kill you, it’ll be worth it,” Edge says.

“well, hell, that’s a better offer than anyone else is giving me,” Sans says. “let’s go.”

Edge strokes his hot cheek and then pulls away.

It's a simple matter to get off the dancefloor. People tend to get out of Edge's way, particularly when he looks annoyed about steering his "drunk husband" towards the car. On their way out, they cross paths with one of the marks, and Edge makes their excuses as Sans grins a charming, loopy grin and leans heavily against Edge's side. Edge can feel him trembling. He doesn't touch the remote to turn it off.

Soon enough, they're out the doors of the club and headed for the parking garage. As the sounds of execrable dance music dies away, he can hear Sans breathing fast and, quieter, the faint hum of the vibrator. He wants nothing more than to tell Sans to take one of his shortcuts, but it’s better not to risk anyone finding out about that unless they have to. They’re supposed to be simple, harmless small-time criminals getting in over their heads, a con artist and his stupid thug.

"tell me you're gonna fuck me in the car," Sans says.

"It's a rental," Edge says.

"look at it this way. it's jizz or dust from when i explode from sheer sexual frustration and take you with me. either way, we're paying for steam cleaning."

"I was under the impression your job was to sweet talk people."

"i tailor it to the customer.” Sans stays back and waits as Edge looks under the car, confirming that no one has gotten ambitious and planted a bomb. “you can't resist a good death threat. makes you melt--"

The car rocks when Edge shoves Sans against it. Sans makes a noise into their kiss, soft and surprisingly sweet, which goes sharp when Edge's thigh slips between his and _grinds_. The vibrator hums against Edge's leg.

"Speaking of melting, those pants are a ruin," Edge says.

"uh-huh," Sans says, his voice a little bit high. He moves against Edge, rubbing off on him like he just can't help it. His trembling hands grasp at Edge's shoulders. "this is cheating, y'know."

"You're the one who wanted to make a friendly wager," Edge says. But then everything is a friendly wager with Sans when he’s bored. _i bet you i can steal that USB right out of that guy's back pocket without him noticing. i bet you that i can break this bastard without you ever having to draw a weapon. i bet you that i can talk this asshole's bodyguards into just letting us walk in and take him. i bet you i won’t come until you’re fucking me._

Edge gives Sans a little more friction and watches hungrily as Sans's head thumps back against the side of the car, color flooding his face. Tenderly, he says, “You expected me to play fair?”

Sans laughs, his eyes squeezed shut. “no. just didn’t know how you’d try to throw the bet.”

“I can stop,” Edge says, and Sans gives him a wild-eyed look that goes straight to his cock. He cradles the back of Sans’s head and kisses him again, murmuring against his mouth. “Go on, then. Beg me to let you come like this where anyone can see.”

Sans huffs out a breath, almost another laugh. His hands move from Edge’s arms down to his ass, pulling Edge closer until they’re practically rutting against each other. It’s probably for the best that the parking lot is deserted because Edge isn’t sure he can stop.

“please,” Sans says. “i’m so fucking wet, can you feel it? i need you in me.”

Still trying to win. Adorable. Edge reaches between their bodies and cradles Sans’s cunt through his pants, pressing the vibrator directly into his clit. Sans jerks, shocked into silence, clutching Edge’s hips, straining up on his toes and getting tenser as Edge gently rocks the vibrator against him until Sans finally sobs out a breath and comes hard. Edge holds him against the car, barely letting him move as he shudders through what seems like a brutal orgasm and then sags heavily, panting, making Edge hold him up.

“wow,” Sans says, out of breath. His grin is a challenge, all familiar trouble, despite the fact that the vibrator is still running and his leg is jittering with overstimulation. “thanks. really sweet of you to take care of me like that. enjoy your blue balls.”

“You like being fucked too much for that to ever be a credible threat, love,” Edge says. After three weeks, the pet name rises too easily to his tongue. He reaches in his pocket and turns the vibrator off. As tempting as it is to force Sans through another orgasm without pause, he wants him still keyed-up and achingly sensitive when he finally slides into him.

Sans looks up at him, his eyes hooded. “well, i can’t really argue with that.”

“I thought not,” Edge says.

With a crooked grin, Sans knocks on the side of the car. “man, it’s really too bad this is a rental, huh? guess you’re gonna have to wait until we get back to the hotel.”

“You are such a pain in my ass,” Edge says, pushing himself upright. He doesn’t give a single fuck about the upholstery, but there’s a difference between getting Sans off through his pants and outright fucking him in a public parking garage. If only his dick got the memo. “Get in the car.”

“okee dokee,” Sans says. They get in the car. Sans fastens his seatbelt, settles in, and proceeds to slide a hand down the front of his pants. When Edge raises a brow, Sans grins. “what? just giving you a little incentive not to dawdle.”

“You’re too kind. Otherwise I might forget what I’m doing,” Edge says. His breath hitches right along with Sans’s as Sans’s hand moves, a little wet noise. “Don’t come again, but feel free to keep yourself entertained.”

“you’re not the boss of me,” Sans says. His hand moves slowly, rhythmically. “except on special occasions. your birthday, gyftmas, our anniversary… hey, what is our anniversary? i know it was a shotgun wedding, b-but--”

That little stutter, Sans aroused enough to stumble over the words that are his weapons, makes Edge shudder like he’s the one being fucked. He puts the car in drive. His tires squeal a little as he backs out of the spot. Gripping the steering wheel to keep from touching Sans, he says, “You’re misremembering, darling. It wasn’t a shotgun wedding.”

“wow, i’m a terrible husband,” Sans says. “lemme try again. married by elvis?”

“No,” Edge says. “We were married on a beach at sunset.”

A pause. After a moment, Sans says, “sunset, huh?”

“Well, you sure as fuck weren’t getting up at sunrise,” Edge says. Sans snorts. “A quiet beach. Only us and our brothers. You wore slippers.”

“oh,” Sans says. The inside of the car is very quiet. Edge can no longer see Sans’s hand moving out of the corner of his eye. “okay. i remember now. it was on that beach at red’s paranoia bunker.” 

“Yes,” Edge says. “Papyrus got one of those online certificates that lets you officiate weddings. He knew exactly what to say.”

“he always does,” Sans says, fondness in his voice. “you cooked.”

“I catered my own wedding?”

“nobody else would’ve met your standards.”

“Admittedly true.”

“you cried.”

“So did you.”

“can’t prove it,” Sans says. “then we went to bed and had wild, headboard-breaking sex.”

“Naturally. What else does one do on their wedding night?”

“i dunno. parcheesi?”

Edge’s gaze drops to the fake wedding ring around his finger. At the start of the job, Red had handed them both to Sans along with a crack about making an honest man of his brother and a scathing sidelong look at Edge like _do i have to do everything myself around here?_ In the end, Sans had handed the ring to Edge, and Edge had put it on himself.

There’s nothing stopping Sans from asking for more from this relationship if he wants it. They aren’t even dating, just sharing a bed. Since the beginning, Sans was blunt about not wanting anything serious, and he seems content without commitment, living in Edge’s back pocket during jobs and then disappearing without a word for days or even weeks at a time when they’re home. Neither of them have said _I love you_ in so many words, just the usual _let me wrap those ribs_ and _stay behind me next time, idiot_.

No. The truth of it: Sans is a goddamn lunatic to have this job. He isn’t a fighter, a fact that he expounds upon at great length whenever someone gives him a chance. He’s a grifter. His job is to end fights before they have a chance to begin, to trespass and spy, to con and manipulate, and to take a shortcut the fuck out of Edge’s way when the shooting starts. But a single backhand slap and Edge could lose him. Their lives are not kind.

_Coward_.

“hey, for the record,” Sans says into his silence. “how about you don’t ever bring up either of our brothers when i’m fingerbanging myself?”

“My apologies,” Edge says. “Please continue.”

“well, now i’m definitely in the mood,” Sans says.

Edge takes one hand off the wheel, reaches into his pocket and turns on the vibrator again. Sans makes a bitten-off noise, and Edge says, “Does that help?”

Sans lets out a long, shaky breath. “yeah, thanks a billion.” Then his hand begins to move again beneath his pants. Edge greatly resents those goddamn pants for depriving him of the view. “drive faster.”

Edge is already going significantly more above the speed limit than is prudent. He can see their hotel from here, the promise of finally fucking Sans sharpening his arousal to a keen cutting edge. He keeps his breathing steady even as Sans’s becomes more and more uncontrolled and his hips move against his hand. Sans is baiting him, and it’s a reflection of Sans’s bad influence that Edge thinks of the pun _masturbaiting_. They clearly spend too much time together.

When they finally park in the hotel garage, Sans pulls his hand out of his pants. His fingers are slick, and he winks at Edge. “you look a little frustrated about something. what’s--”

Edge seizes his wrist. As he lathes Sans’s fingers with his tongue, filling his mouth with the taste of him, Sans stares at him.

“Bed,” Edge says, stroking the inside of Sans’s wrist with his thumb.

“okay,” Sans says.

Only the fact that the elevator is crammed with tourists keeps Edge from shoving Sans against a wall and taking him right there, and even then, it’s tempting. Sans watches him like he knows, an amused tilt to his grin. Nudging the dial on the remote only makes Sans’s smile sharper, as if this is a game he’s winning every time Edge escalates.

Finally, they reach their floor. Sans is a little unsteady on his legs, and Edge puts a helpful hand on the small of his back to steady him. The door doesn’t seem to have been touched since they were gone, the device that Papyrus told them to plant on the doorframe untriggered. Edge listens at the door, then gently nudges Sans behind him before he pushes the door open.

Nothing stirs. Edge steps in; Sans remains behind, slouched against the wall beside the door, using it for cover. Once Edge has swept the room and is satisfied, he says, “It’s fine.”

Sans strolls in, kicking the door shut. With one negligent wave of his hand, he grabs Edge by the soul and tosses him onto the bed. Edge allows it, watching with equal parts amusement and hunger as Sans takes off his pants. The harness that came with the vibrator, meant to hold it in place against Sans’s clit, started out incongruously pink, but now it’s wet and blue wherever it came in contact with his cunt. He’s soaked, his thighs slick with it. He’s beautiful.

“hey, baby,” Sans says, straddling Edge’s thighs. His voice is husky, fucked-out. The vibrator hums between them as Sans grinds absently against him. “are we in tennessee? because you’re the only--”

“You already have me. Spare me the terrible pickup lines.” Edge unbuckles his belt and then drags his zipper down. Before he can take his dick out, Sans does it for him. Edge twitches involuntarily into his hand, and Sans grins, thoroughly pleased with himself, thumbing the slit. Edge grinds his thigh up into Sans to regain his attention, making him jerk, and then says, “Do you want it badly enough to work for it?”

“that’s cruel, edgelord,” Sans says, moving to line Edge up to his cunt. Slowly, he sinks down, easing Edge into his wet, decadent heat. His eyes burn, drinking in Edge’s every microexpression. “i want a divorce.” 

Edge takes him by the hips and pulls him down hard, all at once. Sans groans, low and grateful. Stroking Sans’s iliac crests with his thumbs, Edge says breathlessly, “You like it when I’m cruel.”

“yeah,” Sans sighs. He rocks his hips, an experimental motion, and shudders. “fuck, that’s good. thanks.”

“You’re welcome,” Edge says, using his grip on Sans’s hips to encourage him to move. Sans is light enough for Edge to just use him like a toy, but he’s enjoying the sight of Sans moving above him, the slow blush creeping up Sans’s spine, the faint sheen of sweat rising on his bones.

Bracing himself with one hand on Edge’s sternum, Sans rides him. His eyes squeeze shut, an expression of concentration like he’s picking the lock on a complicated safe. His pace is maddening. Unsteadily, Sans says, “‘m not thanking you. i’m thanking the universe. a billion years of evolution to make one perfect dick.”

“Perfect,” Edge echoes, delighted by this ammunition Sans has so kindly provided for future arguments. He urges Sans a little faster, rocking up into him as he grinds down.

Sans shivers, his fingers knotting in Edge’s shirt. Edge can see he’s already close from the still-humming vibrator and the teasing in the car, his cunt twitching in the promise of another orgasm. Despite that, he keeps running his mouth. “don’t get cocky. you had nothing to do with-- oh fuck, edge--”

That break in his voice is too much temptation. Now Edge takes control, rolling them both over so that Sans is on his back on the sheets, Edge above him. The shift in angle makes Sans cry out and then clamp a hand over his own mouth. Edge pulls his hand away, pinning his wrist to the bed, and fucks into him hard to hear him make that unguarded noise again. 

Once Edge feels the first sweet spasm of Sans around him, it’s too difficult to stop. He waited too long for this, fiddling with the dial on the remote all night to watch Sans’s reaction from across the room, the interlude in the parking garage, watching Sans fuck himself in the car. He wants it too much. His pace is punishing, but Sans is all enthusiastic welcome, gasping out delirious nonsense. “just like that, don’t stop, please, _please_ \--” 

As if Edge would ever deny him. He hitches one of Sans’s legs around his hip, allowing him to sink deeper on the next thrust, and Sans stiffens beneath him. His silence is so sudden and so profound that Edge almost hesitates, until Sans whimpers, tightening around him in unmistakable release. The hot clutch of his cunt demands Edge’s release in return, wringing it out of him. They shudder through it together, long and drawn out, their ragged breathing the only sound in the room. 

Eventually, Sans shoves his hand between them, extracts the vibrator bullet and flings it to the side. It continues humming from the floor. Sans unwinds beneath him, exhaling a long, slow breath. Edge suppresses his smile and asks, “You don’t want to go again, then?”

“you can do whatever you want, buddy,” Sans says, eyes closed. “my body is your playground. play on the swings. use the teeter-totters. get a friction burn from the slide. really go nuts. just don’t expect me to stay awake for it.”

“I’ll bear that offer in mind,” Edge says. Sans hums agreeably.

Edge’s eyes drift to the deceptively fragile wrist that he’s pinning down and then to the ring on Sans’s finger. It looks ridiculous. He would never get Sans simple gold. Too easy to scratch, too common, too _normal_. He would get him something in damascus steel, beautiful but solid enough to take a bullet without shattering.

Not that he’s considered this at length.

… goddamnit, that was a terrible pun.

Reluctantly, Edge releases Sans’s wrist and moves off of him. Sans stays exactly where he is, even when Edge nudges him and says, “We should debrief.”

“thought we just did.”

“About what you observed at the club,” Edge says. “We are still here on a job.”

“nothing that interesting. gimme ten minutes to nap.”

“Red’s going to expect a report.”

“tell him we were too busy having sex.”

“Of course,” Edge says dryly. “I’ll ask him to get Papyrus on the conference call and we can give them all the sordid details at once.”

Sans grimaces, as Edge knew he would. Then, with passive-aggressive slowness, he sits up. Edge’s gaze moves involuntarily to between Sans’s legs, where red magic is trickling out of his cunt, and then back to find Sans watching him. Somehow Sans manages to smirk without ever actually changing facial expression. He has a gift.

“i’ll give you the rundown in the shower,” Sans says. “i’m kind of a mess. dunno how that happened.”

“I can’t imagine, but I’m sure it’s your fault somehow,” Edge says.

Sans shrugs, then gets up with an overdramatic grunt and makes his way to the bathroom. He stops with his hand on the door handle, not looking at Edge when he says, “our anniversary is april 21st.”

April 21st. Prague, last year, the job where Sans barely avoided getting killed by some idiot with a gun. The night they’d first fallen into bed together, just trying to find some comfort. Edge didn’t know Sans kept track of the exact date. He says, “I thought it was December 17th.”

The day they met, two years ago now, Edge resentful of this stranger that was supposed to replace his brother in the field until Red recovered, Sans a cypher of bad jokes and infuriating nonchalance. Edge had no idea then what was coming or how much Sans would joyfully disrupt his deliberate, measured life.

Sans gives Edge a grin over his shoulder. “maybe one of these days, we’ll figure it out.”

He goes in the bathroom, leaving the door open. A moment later, Edge hears the shower start. An invitation to join him, if he’d like. No pressure. Sans is very good at no pressure. Edge rises and follows him, as he always does, closing the door behind them.

**Author's Note:**

> content warnings: reference to a monster trafficking ring that has already been shut down.


End file.
